First of all: thanx for all your advice!

I have been trying all your suggestions, but it still didn't work.
Then, when I was about to throw everything out the window, I suddenly saw a
little led flash!
I really don't know, what did the trick......but I guess it was the default
RC mode and maybe the load of the capacitors.
Maybe  tomorrow I will replace the caps to the ones I used before (47pF) and
see if it still works.

The rest of the evening I'm gonna sit on the couch with my flashing led and
let my roommate make fun of me :)

Thanx again,
I'm happy!

John